Work Text:
“Oh, you’re up!” His mom, a flurry of activity as she moved around the kitchen, packing tupperware into two bags, pouring coffee into thermoses, and taking bites of a piece of toast. She was dressed, deep green scrubs pristine and crisp, hair drawn back into a tight bun, hospital tags declaring her Head ER Nurse hanging from her neck. “Good. We’re leaving early, there was a villain incident early this morning and it’s all hands at the ER for the civilians coming in.”
Katsuki stood up straighter, the last vestiges of sleep falling away. “What-”
“Nothing for you to worry about.” Her response was quick, firm, and the narrowed eye look she tossed over her shoulder full of warning. “It’s already been cleaned up by heroes, it’s just tending to the wounded now. You and Izuku stay home, and out of trouble.”
Katsuki made a face but didn’t argue with her; he would check it out online but if it was really all over then it wasn’t his business. Instead he slipped deeper into the kitchen and began to help, pouring cooled soup and packing up rice for her. She murmured her thanks, dropping a kiss to his shoulder as she bustled by. He grumbled and twisted away from her, smiling slightly as her bright laughter filled the kitchen.
“Your mother is giving me a ride in, and heading into the studio. We’ll probably stay in town overnight, if things are as bad as they seem.” She continued, scooping up the containers to pack them up. “There’s omelets already rolled and I left money on the microwave, so you two can order pizza for dinner.”
“Okay.” He said, focus on the plate of eggs and rice he’d just uncovered. He popped a piece into his mouth, listening with half an ear and nodding to what his mom was saying.
“I noticed you weren’t talking at dinner last night, so I want you two to stay in and spend some time together today. I know Izuku’s feelings were hurt yesterday, and you might not understand, but it’s no good for brothers to fight.” She said. Katsuki nodded, chewing slowly. “Especially not if we’re going camping at the end of the summer. I don’t want our last family trip before you graduate and leave home to be miserable.”
“Sure.”
“Katsuki, look at me.” Her scent was soft, floral and powdery fresh in a way that never failed to put him at ease, even when he was being scolded, even when her voice took on that sharp note that demanded his attention. He turned, found her at his back, peering up at him through the fringe of her hair. She reached up, caught his face between her small, rough hands, and tugged him down so they were eye to eye. “Listen to what I’m saying.”
If it was his mother doing this he would scoff, curse at her while squirming of her grasp, shout at her to not touch him and mind her business before leaving the room, hopefully avoiding having something chucked at his head. That was how they’d always been, ever since he was a little kid and hadn’t yet presented as an alpha; they clashed, argued, their tempers flared and exploded, and more often than not things got resolved by ignoring them until they fizzled out and moved on. But Mom wasn’t like that; she was patient, warm, commanded attention with quiet words, and soothed things by talking them out, and liked to send him off with a hug and a reminder that even when she was upset she loved him.
He couldn’t begin to count how many times she’d come between him and his mother, settled them and lead them to work things out before they’d even realized it was happening. She was emotional, they all were really, but somehow that made her strong. Katsuki didn’t understand it anymore now than he had growing up, just knew it as a fact of life. When Inko spoke he listened, when she made demands he complied, when she fixed her eyes on him he froze, calmed, and was willing to wait.
Izuku took after her to a degree, in so far as he was able to lead others to outcomes and conclusions they hadn’t even known they were looking for, but a lot like their mother as well. Izuku got angry slowly, but when he did he exploded the same as Katsuki did, burned just as hot and furious, in a way people said omegas didn’t, or couldn’t. Just like Katsuki had inherited Inko’s freckles, pale as they were over his nose and cheeks, Izuku had gotten bits of Mitsuke as well, neither of them the perfect copy of their same-dynamic parent that people might assume.
“I’m listening.”
“You need to be careful with your brother. You’ve been his hero your whole lives.” She pressed her hands tighter to his face, held him firmly in her grasp. “He looks up to you, even now, and I think he always will. The things you say mean more to him than anything else, because you’re his brother and the major alpha presence in his life. If you tell him he’s ugly, and that no alpha would pay him any mind, that’s what he’s going to believe. You hurt his feelings badly yesterday, and you need to make up for it.”
If she knew what had happened the day before, that Izuku had slipped into his room, into his lap, and forced Katsuki’s hands under his shirt, made him touch and practically grope his chest and ass, that Katsuki had gotten hard with his hands on his own twin, she wouldn’t be saying any of this. No, she’d be angry with him, disgusted, would be trying to seperate them like they had when they were young and Katsuki was too clingy, too close. Maybe she’d even put him out of the house for being a twisted pervert, for somehow pushing that long lingering sickness in him onto Izuku.
His eyes dropped away from her ernest face. His ears burned with shame. “Mom.”
She laughed again, sweetly, not understanding. “I know I know, but listen. I know you don’t mean to be mean, you’re like Mitsuki, but...you’re just starting to get along again. I want things to stay that way. You need each other. Try to apologize, spend some time together. For me.”
He nodded numbly. “Okay.”
---
“Morning Niisan.” Izuku chirped. Katsuki, sprawled on the couch and flipping distractedly through the channels, looked up. Stopped. Stared harder, mouth dropping open in surprise. His brother was fresh from the shower and hadn’t, it seemed, wanted to bother getting dressed beyond the short towel wrapped around his lower half.
“Deku!” Katsuki rasped, throat suddenly dry and tongue thick in his mouth.
Izuku hummed in acknowledgement, head tilting to the side and eyes peering out from the curtain of sodden curls hanging over his face. He was toweling his hair dry, but paused for a moment to smile at him. “Hmm? Are the moms gone already? I wanted to talk to them, about the camping trip.”
Katsuki opened his mouth then shut it, unable to come up with anything to say.
Calling it a towel was, on second thought, too generous. It was more like a large washcloth, barely big enough for the ends to be tucked together at his waist, just below where the deep V abs meeting obliques, and that was the only point the two ends met. From there they pulled apart, exposing the whole of one of his legs, surprisingly thick, shapely, and well muscled thigh, skin slightly lighter than the rest of Izuku’s body, little constellation groupings of freckles here and there. When he padded closer to the couch, arms up as he toweled off his dripping curls, the towel shifted and Katsuki saw a hint of green before he forced his eyes back up to a more acceptable level.
Except no safety was to be found there either. Bare chested, skin dewy with beads of water sliding down slowly from his hair in thin trails. Izuku’s shoulders were wide, chest thick, and tapering down to abs and a thin waist, littered with overlapping scars and that was all fine, no big deal. If it was two days ago Katsuki would have thought nothing of him, would have glanced and looked away with no thoughts out of the ordinary, but now...now he’d had his hands on Izuku, had felt warm soft skin and stiff little peaks. He sought them out without meaning to, while hating himself, zeroed in on his twin’s breasts. They were small, barely there when just looking, a slight rounding of his pecs, tiny perky swells and dusky pink nipples. There was a spray of freckles across his chest, a twisting curl that curled over and then crept across the underside of his breasts, crept to the edge of his nipple, and then between them.
Back down, for his own sanity, and he was looking at that stupid towel again. It was so so short, the bottom edge looked to be not quite hitting the bottom curve of Izuku’s ass.
“Kacchan?” Izuku was at the couch, hip cocked and hands at his sides, second towel hanging around his shoulders. “Are you listening to me?”
He smelled good, scent strong and clean after his shower, that citrus sweetness and brightness that was unique to Izuku heavy in the air, with an undercurrent of omega that sat heavy of Katsuki’s tongue. That preheat smell, musky and tempting, tickled his nose.
Katsuki’s stomach dropped and his cock, dedicated to being a traitor, started to harden in his pajama pants. It was too much, unbearable when Izuku was standing before him, looking like that, smelling like that, close enough to reach out and grab. Spit pooled in his mouth, under his tongue; Katsuki’s fingers dug into the couch.
“Where are your fucking clothes?!” Katsuki spat, hating how high and tight his voice was, how hard his heart was beating, himself for being breathless and hot before his twin.
“I was so hot after my shower, and it’s just us right? So I thought I’d get dressed later.” Izuku was all innocence, eyes going wide and round. “It’s not a problem, is it? I didn’t think you’d care.”
Katsuki swallowed hard. “I...you...your tits are fucking out.”
Izuku’s lips twitched upwards. “I thought you said I didn’t have any.”
“Fuck off.” Katsuki snarled. “I said I was sorry.”
Izuku shrugged. “Still. There’s no problem, right? It’s not like you’re looking.”
Katsuki couldn’t even find it himself to glare or continue to meet his brother’s gaze. He looked away, disgusted and guilty, but didn’t miss the way Izuku’s eyes narrowed and his nose twitched, flared as he breathed in, and pink lips parted around a soft noise. His eyes darted down Katsuki’s body, hesitated near his lap, before coming back to meet his gaze. Katsuki’s face burned, first with mortification and then with indignation and anger; where did Izuku get off looking at him like that when he was the one doing all of...this? And yesterday, crawling all over him and having Katsuki touch him, in some weird attempt to prove that he was ‘an omega’.
Sleeping in his bed the night before, pressing up against him, smelling like preheat and so hot and soft as he rubbed his ass against him and-
Was this some sort of game to him? Mess with Katsuki, knowing that he’d been...all wrong where Izuku was concerned since they were toddlers and he couldn’t keep himself from biting and clinging to his younger twin, no matter how many people told him not to. Did Izuku know that when Katsuki had become cruel and hateful it was because they’d finally presented and all of Katsuki’s instincts had gone haywire, telling him things about his brother, about his sweet fruit scent and sun bright smile and familiar presence, that his brain knew were wrong.
Did Izuku have any idea how hard things were him, even now, when he couldn’t resist chasing away the people interested in Izuku, that he still longed to be the only one his brother saw. That he was terrified that Izuku wouldn’t need him anymore?
“Niisan,” Izuku started, voice husky and strange. “Is something wrong?”
He grabbed his twin by the arms and yanked him forward, down to his level. The towel, the only barrier between Izuku and nudity, came undone and fluttered to the ground. They both looked down, Izuku squeaking in surprise, then back at each other. His twin’s cheeks went pink. Katsuki’s breathed in, swallowed the taste of of embarrassment and a faint lick of arousal that spiked in his brother’s scent, and lunged forward.
Izuku’s mouth tasted like mint, was hot against his own and then wet went lips opened for him, invited him to taste deeper. He held tight to the omega, wrenched him down and twisted them around, pinning Izuku beneath him. He made himself a place between thick thighs, using a hand to urge Izuku into the position he wanted.
“Niisan!” His twin yelped into his mouth, onto his tongue. “Hah, wait wait, what-”
“Shut up.” Katsuki ground out, drawing back enough to glare down at Izuku. “Do you think I’m so fucking stupid I can’t tell what you’ve been doing?” I
zuku’s eyebrows jumped up and then he had the nerve to try and look confused, shaking his head in denial. Katsuki growled then, feeling wild and angry, burning up inside, thrust a hand between them, between Izuku’s legs, skimming over his cock and going right for his cunt. Wiry curls parted under his touch and then heat, beckoning but forbidden, and he was swiping at the seam, rubbing the nub of his twins clit before moving on.
His brother jerked underneath him, mouth forming an O of shock then snapping shut with an audible click of teeth. Katsuki found where his brother was damp, thin slippery moisture hidden away by bloodwarm folds, and plunged his fingers inside without further warning. Izuku yelped again, legs shutting almost painfully tight around Katsuki, as his head snapped back. He pressed in deeper, harshly, spread his fingers apart against Izuku’s clenching insides. He was hot silk inside, wet and getting wetter with each thrust of Katsuki’s fingers, and so tight it was hard to keep a steady pace. This was all wrong but as he worked his brother open on his fingers, felt slick squishing around the digits with each hard thrust, the shame only made him want him more. It burned him, filthy poison coursing stronger through his veins with each hummingbird fat beat of his heart, made his vision blur, and gums itch.
Katsuki twisted his hand, crooked his fingers forward, and pressed up, sliding over convulsing muscle searchingly. Blood pounded in his ears and heat bubbled in his stomach, blood filled his cock, had him so hard it hurt in record time.
“This is what you wanted, right?” Katsuki asked, pounding his brother’s pussy, palm slapping against the stiffened nub of his clit wetly. “You want big brother to fuck you, Deku? That’s why you’re out here with your cunt out, flashing it at me, isn’t it? Disgusting.”
Izuku panted under him, something that almost sounded like “Hurts” before falling into a whimpering gasp. His nails raked at Katsuki’s neck and shoulders as his legs jerked and the heels of his feet dug into the couch. Katsuki watched his shut his watering eyes and, on an impulse, dropped his head to lick away the first tear that slipped free.
He pressed a third finger into his brother’s cunt, a cold tingle running up his spine when Izuku’s back bowed and slick ran out over his fingers, wet his palm. He spread his fingers on the push in, and chased salt from Izuku’s face with his tongue, shared it with him in another deep, drobing kiss.
When he pulled his fingers out his brother Izuku’s eyes cracked open, wet behind clumped eyelashes, watching silently as Katsuki pushed down his shorts just enough to get his cock free to the cool air. Katsuki didn’t waste any time lining himself up, aiming the head of his cock for his twin’s hole and sliding inside the loosened entrance once he was there.
Izuku was open mouthed, groaning, digging his nails into him so deep Katsuki was sure he was drawing blood, and wrapping his long legs around him, drawing him close as his cunt sucked Katsuki’s cock in. A snap of his hips buried him down to the hilt, itching, stretching skin around where his knot was starting to grow and all.
Izuku wailed, head thrown back and eyes wide, and he bore down on Katsuki so hard he was a little afraid he was going to lose his dick. Who knew, with that inherited quirk of his, what was and wasn’t possible.
Katsuki pressed his fingers, slick drenched, to Izuku’s open mouth, delved in past his lips and over his tongue, spread the slippery moisture over the surface.
“Clean them up Deku.” He rocked his hips, ground down slowly, and felt his brother convulsing around him. Pink, swollen lips closed around his fingers and Izuku’s tongue moved over them, swiping up, down, between them. His cheeks hollowed; Katsuki’s heart clenched. “Ah, yeah, like that. Suck them like you’ve been wanting to suck my dick.”
He fucked his brother hard with his fingers and his cock, pounding into him with all the frustration and anger in him, moved them so he’s got Izuku practically bent in half, one leg hooked up over his shoulder. He moved with short, powerful thrusts, barely leaves Izuku’s body before he slams back in, and pulls helpless cry after cry from his brother’s throat. He looks so good like that, sobbing, red faced, cock hard and dripping over his belly, cunt pink and stretched wide around Katsuki’s cock, stretching wider when his inflating knot forced its way back in over and over. Katsuki watched, bile sour in the back of his throat, his dick piston in and out, listened to the obscene squelch of their bodies come together, and wondered wildly if this was always where they were headed.
Was coming together like this, closer than they’d been even in the womb, inevitable?
When Izuku came, spurting white over his stomach and tightening around him like a vice, caught his knot and squeezed it just right, and Katsuki followed with a shout, he thought that maybe, yes, it had been.